Dry-seal pressure-type gasholders



Jan. 26, 1965 F. w. HORNER, JR 3,167,412

DRY-SEAL PRESSURE-TYPE GASHOLDERS Filed Feb. 16, 1962 2 Sheets-Sheet 1,1; INVEIJTOR WALTER HORNE/i, JR.

& ATTYS.

Jan. 26, 1965 F. w. HORNER, JR

DRY-SEAL PRESSURE-TYPE GASHOLDERS 2 Sheets-Sheet 2 Filed Febl6, 1962 ilivvliilltil'flililiilli INVENTOR.

E WALTER HORN/FR, JR.

,5 p & ATTYS.

United States Patent Ofiice 3,167,412 Patented Jan. 26, 1965 3,167,412DRY-SEAL PRESSURE-TYPE GASHOLDERS Frank Walter Horner, Jr., Park Ridge,111., assignor to General American Transportation Corporation, Chicago,111., a corporation of New York Filed Feb. 16, 1962, Ser. No. 173,696 14Claims. (Cl. 48-174) The present invention relates to dry-seal pressuretype gasholders, and more particularly to improved diaphragms for suchgasholders.

A dry-seal pressure-type gasholder conventionally comprises a containerincluding an upstanding substantially cylindrical shell or side Wall, asubstantially disk-shaped piston arranged in the container and movablein the vertical direction, an upstanding substantially cylindricalfender carried by the piston adjacent to the circumference thereof andspaced radially inwardly with respect to the shell to provide an annularspace therebetween, and an annular curtain-like gas-impervious flexiblediaphragm arranged in an upwardly directed annular loop in the annularspace. In the arrangement, the diaphragm includes an annular outer wallsealed adjacent to the bottom thereof to an annular portion of theshell, an annular inner wall sealed adjacent to the bottom thereof to anannular portion of the piston, and an annular connecting wall extendingbetween the top of the outer wall and the top of the inner Wall, wherebythe gas pressure in the container presses the outer wall into firmengagement with the inner surface of the shell and presses the innerwall into firm engagement with the outer surface of the fender. When thepiston rises in the container, the material in the diaphragm is fed fromthe inner wall through the connecting wall into the outer wall; andconversely, when the piston falls in the container, the material in thediaphragm is fed from the outer wall through the connecting wall intothe inner wall. Since the circumferential length of the inner surface ofthe shell is necessarily greater than the circumferential length of theouter surface oflthe fender, the outer wall of the diaphragm has atendency to have a circumferential length that is greater than thatofthe inner wall of thediaphragm; with the result that folds, wrinkles andcreases tend to form across the looped part of the diaphragm. Thiscondition of the diaphragm is most objectionable as it leads to earlypuncture and mechanical failure of the diaphragm in the normal operatingcycle of the piston. In order to prevent such wrinkling of the materialin the diaphragm as it is fed between the outer and inner walls thereof,many elaborate constructions of the diaphragm and of the associatedfender have been employed heretofore, as disclosed in US. Patent No.2,723,908, granted on November 15, 1955, to John H. Wiggins, John W.Allen and F. Walter Homer, and in US. Patent No. 2,756,132, granted onJuly 24, 1956, to John H. Wiggins. While these arrangements arereasonably satisfactory in the operation of the gasholder, they areentirely too expensive to manufacture and to maintain in service.

Accordingly, it is the general object of the present invention toprovide in a gasholder of the type described, an improved and simplifieddiaphragm that is economical to manufacture and that requires noexternal devices or appliances to prevent wrinkling of the materialtherein incident to the feed of the material in the diaphragm betweenthe outer and inner walls thereof.

Another object of the invention is to provide in a gasholder of thetypedescribed, an annular flexible diaphragm arranged in an upwardlydirected annular loop in the annular space between the shell of thecontainer and the fender carried by the piston arranged therein,

wherein the diaphragm has an unstrained circumferential length Cd thatis less than the inner circumferential length Cs of the shell and thatis greater than the outer circumferential length Cf of the fender,whereby the gas under pressure in the container produces circumferentialtension strains in the material in the outer wall of the diaphragm so asto stretch the same to a circumferential length substantially equal toCs without effecting wrinkling thereof and so as to press the thusstretched outer wall into firm engagement with the inner surface of theshell, and whereby the gas under pressure in the container producescircumferential compression strains in the material in the inner wall ofthe diaphragm so as to compress the same to a circumferential lengthsubstantially equal to C without effecting wrinkling thereof and so asto press the thus compressed inner wall into firm engagement with theouter surface of the fender, with the result that the vertical movementof the piston elfeets the feed of the material of the diaphragm betweenthe outer wall and the inner wall through the connecting wall and theconsequent reversal of the circumferential strains in the material thusfed.

' A further object of the invention is to provide in a gasholder of thetype described, a diaphragm of improved composite construction, wherebythe same possesses as inherent characteristics thereof the previouslydescribed elastomeric qualities.

A still further object of the invention is to provide a diaphragm for a,gasholder, wherein the diaphragm is of composite sandwich constructionincluding an inner layer of material in contact with the gas stored inthe container and an outer layer of material in contact with theatmosphere, wherein the materials of the two layers mentioned areespecially selected for the special properties thereof that render themsubstantially ideally. suited to the environmental operating conditionsrespectively encountered thereby, and wherein the materials of the,

two layers mentioned are so coordinated that the diaphragm as a wholepossesses the previously described elastomeric qualities. 1

A further object of the invention is to provide a diaphragm of the typedescribed that essentially comprises a gas-impervious inner layer and aresilient outer layer intimately bonded together, wherein the innerlayer is formed of elastomeric organic material that is chemically inertto the gas stored in the container and that is char.- acterized bysubstantial stretchability in the circumferential direction of thediaphragm, and wherein the outer layer is formed of elastomeric organicmaterial that is resistant to atmospheric gases and to water vapor andthat is characterized by both substantial stretch-ability andsubstantial compressibility in the circumferential direction of thediaphragm.

A further object of the invention is to provide a diaphragm of the typedescribed that further comprises an intermediate layer of adhesivefirmly securing together the inner and outer layers noted, wherein theintermediate layer is formed of organic material that is characterizedby substantial flexibility after setting thereof. 7

Yet another object of the invention is to provide a diaphragm of thetype described, wherein each of the layers noted essentially comprisesan elastomeric material that is in the form of a synthetic rubber or asynthetic organic resin having the general properties of a syntheticrubber.

A further object of the invention is to provide in a gasholder, adiaphragm of the type described that incorporates a textile fabric thatis elastic and that is characterized by exceedingly great tensilestrength in the radial direction between the outer and inner perimetersthereof that are respectively sealed to the shell and to the piston inthe gasholder.

A still further object of the invention is to provide a gaspiston typeincluding a number of nested pistons movable in the vertical directionand also including a corresponding numberof flexible diaphra'gms of thetype specified.

Further features of the invention pertain to the particular arrangementof the elements of the gasholder and of the diaphragm incorporatedtherein, whereby the above-outlined and additional operating featuresthereof are attained. p I

The invention, both as it is organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the follow ing specification, taken inconnection with the accompanying drawings, in which: 7

FIGURE 1 is a fragmentary plan view, partly in horizontal section, of adry-seal pressure-type gasholder incorporating a diaphragm embodying thepresent invention;

FIG. 2 is a fragmentary vertical sectional view of the gasholder, thisview being taken in the direction ofthe arrows along the line 2-2 inFIG. 1;

FIG. 3 isa fragmentary vertical sectional view, similar to FIG. 2, of amodified form of the gasholder that is provided with the two nestedpistons and incorporating FIG. 6 is a greatly enlarged sectional view,similar to gasholder 10 there illustrated and embodying the features ofthe present invention comprises a container 11 that includes anupstanding substantially cylindrical outer wall or shell 12, asubstantially disk-shaped bottom wall or .floor 13 and av substantiallycone-shaped top wall or roof 14; which container 11 is adapted tocontain and to store under pressure such gases as natural gas, lightpetroleum gases,.coke oven gas, etc. The stored gases have a widevariety of compositions; for instance, coke oven gas essentiallycomprises methane','hydrogen, carbon dioxide, carbon monoxide, hydrogensulfide, oxygen, nitrogen and aromatic compounds including benzene,toluene and pyridine, and adulterant compounds such as carbon disulfideand mercaptan sulphur. Also, the gasholder 10 comprises a substantiallydisk-shaped piston 15 arranged in the container 11 and movable in thevertical direction; which piston 15 carries adjacent to thecircumference thereof an upstanding substantially cylindrical fender 16that is spaced radially inwardly with respect to the shell 12 to providean annularspace 17 therebetween.

An annular curtain-like gas-impervious flexible diaphragm 20 is arrangedin an upwardly directed annular loop in the annular space 17; andthediaphragm 20 essentially comprises an annular outer Wall 21 and anannular inner wall 22 and an annular connecting wall 23. The bottom ofthe outer wall 21 is sealed to an annular portion of the shell 12 by anassociated annular sealing bar 31; and the bottom of the inner wall 22is suitably sealed to an annular portion of the piston 15 adjacent tothe bottom of the fender 16. The top of the outer wall 21 integrallyjoins the outer looped portion of the connecting wall 23; and the top ofthe inner Wall 22 interally joins the inner looped portion of theconnecting wall 23. The gas contained in the gasholder 10 is storedunder pressure in the lower portion of the container 11 below the piston15 and the diaphragm 20; whereby the lower or inner side of thediaphragm 20 is in cont-act with the stored gas. The upper portion ofthe container 11 above the piston 15 and the diaphragm 20 is vented tothe atmosphere, usually through a series of vent devices, not shown;

whereby the upper or outer side of the diaphragm 20 isin contact Withthe atmosphere.

When the container 11 is empty of stored gas, the piston 15 occupies itslower portion, as illustrated in full lines in FIG. 2; when thecontainer 11 is full of stored gas, the piston 15 occupies its upperposition, as illustrated in broken lines in FIG. 2; and when thecontainer 11 is partially full of stored gas, the piston 15 occupies anappropriate intermediate position with respect to its lower and upperpositions noted. The piston. 15 in its lower position is supported onthe floor 13; and the piston 15 in its upper position is disposed nearthe roof 14, the upper position of the piston 15 being established by avolume control safety vent, not shown. In the operation of the piston 15in thevertical direction between its lower and upper positions, asubstantially constant pressure is maintained upon the stored gas in thecontainer 11; which pressure of the stored gas is normally held ormaintained at about 20 water gauge. Also the gas under pressure storedin the container 11 forces the diaphragm 20 into its upwardly directedannular loop-like configuration, so as to press the outer wall 21 of thediaphragm 20 into firm engagement with the adjacent portion of the innersurface of the shell 11 and so as to press the inner wall 22 of thediaphragm 20 into firm engagement with the adjacent portion of the outersurface of the fender 16. As the piston 15 falls in the container 11,the material in the outer Wall 21 of the diaphragm 20 is fed-off of theinner surface of the shell 12 through the connecting wall 23 into theinner wall 22 and is thus pressed into firm engagement with the outersurface of the fender 16. Conversely, as the piston 15 rises in thecontainer 11, the material in the inner wall 22 of the diaphragm 20 isfedoff of the outer surface of the fender 16 through the connected wall23 into the inner wall 21 and is thus pressed into firm engagement withthe inner surface of the she1l12. In the gasholder 10, the shell 12 hasan inner radius Rs, 'as illustrated in FIG. 2, and a corresponding innercircumferential length Cs. Similarly, the fender 16 has an outer radiusRf, as illustrated in FIG. 2, and a corresponding outer circumferentiallength C The diaphragm 20 has an unstrained radius Rd, as illustrated inFIG. 2, anda corresponding unstrained circumferential length Cd. In thearrangement, the relationship exists: 1

Cs Cd Cf the container 11 produces circumferential tension aSClcompression strains in the material in the walls of the diaphragm 20 asthe verticalmove'ment of the piston 15 effects the feed of the materialof the diaphragm 20 between the outer wall 21 and the inner wall 22thereof through the connecting wall 23 thereof and the consequentreversal of the circumferential strains in the material of the diaphragm'20 thus fed.

In a very small gasholder 10 of about 50 cu. ft. Cs is equal to about104% of Cf, whereas in a relatively large gasholder 10 of about5,000,000 cu. ft. Cs is equal to about IOU/4% of C The unstrainedcircumferential,

length Cd of the diaphragm 20 is equal to about /2 (Cs-f-Cf); wherebythe material of the diaphragm 20 is.

' stretched circumferentially by about 0.6% to about 2% of Cd and iscompressed circumferentiallytby the same percentages all withoutinducing wri kles aC looped portion of the diaphragm 20. v I

In constructing the gasholder 10, the diaphragm 20 is fabricated from aplurality of straight runs of material into a composite ring having atotal internal circumferential length and a total externalcircumferential length of approximately Cd in unstrained condition ofthe material. The thus fabricated diaphragm 20 has an inner side and anouter side that are different from each other, as explained more fullyhereinafter; whereby the composite diaphragm 20 is then placed in theannular space 17 between the shell 12 and the fender 16 and with theinner side in downward position so that ultimately it will be in contactwith the gas stored in the container 11. The bottom of the outer wall 21of the diaphragm 20 is suitably stretched to the circumferential lengthCs and is suitably secured to the shell 12 appropriately above the floor13, utilizing the sealing bar 31. The bottom of the inner wall 22 of thediaphragm 20 is then suitably compressed to the circumferential lengthCf without inducing wrinkles across the looped portion of the diaphragm20 and is suitably secured to the piston 15 adjacent to the bottom ofthe fender 16. Accordingly, at this time, the bottom of the inner wall22 is compressed with respect to the unstrained circumferential lengthCd thereof and into the circumferential length Cf, while the bottom ofthe outer wall 21 is stretched with respect to the unstrainedcircumferential length Cd thereof and into the circumferential length.Cs, without inducing wrinkles in the diaphragm 20. Subsequently, whenthe gas to be stored in the container 11 is introduced thereinto belowthe piston 15 and the diaphragm 20, the diaphragm 20 is blown into itsnormally upwardly directed annular looplike configuration, as shown inFIG. 2. At this time, the remainder of the outer wall 21 of thediaphragm 20 is stretched to the circumferential length Cs and ispressed into firm engagement with the inner surface of the shell 12, andthe remainder of the inner wall 22 of the diaphragml-U is compressed tothe circumferential length Cf and is pressed into firm engagement withthe outer surface of the fender 16, all without inducing wrinkles in thediaphragm 20.

Referring now to FIG. 3, the modified form of the gasholder 110 thereillustrated is basically the same as the gasholder 10, as describedabove in conjunction with FIGS. 1 and 2 except that in this case, thepiston is of composite construction including two piston sections 115Aand 115B arranged in nested relation. More particularly, the outerpiston section 115A is spacedradially inwardly with respect to the shell112 of the container 111 and the inner piston section 11513 is spacedradially inwardly with respect to the outer piston section 115A. Theouter piston section 115A carries an upstanding substantiallycylindrical fender 116A, and theinner piston section 115B carries-anupstanding substantially cylindrical fender 116B. Also, the diaphragm isof composite construe:

tionincluding two diaphragm sections 126A and 120B arranged in nestedrelation. Specifically, the outer diaphragm section 120A is arrangedbetweenthe inner surface of the shell 112 of the container 111 and theouter surface of the outer fender 116A; while the inner diaphragmsection 12013 is arranged between the inner surface of the outer fender116A and the outer surface of the inner fender 1163. Accordingly, theouter diaphragm section 12tlA includes an annular outer wall 121A thatis sealed adjacent to the bottom thereof to an annular portionof theshell 112, an annular inner wall 122A that is sealed adjacent to thebottom thereof to an annular portion of the outer piston 115A, and anannular connecting wall 123A extending between the top of the outer wallnular inner wall 122B that is sealed adjacent to the bottom thereof toan annular portion of the inner piston B,

and an annular conecting wall 123B extending between the top of theouter wall 121B and the top of the inner wall 122B.

The inner piston 11513 has a lower position, illustrated in full linesin FIG. 3, wherein it is supported upon the floor 113 of the container111; and the outer piston 115A has a lower position illustrated in fulllines in FIG. 3, wherein it is supported upon associated structure 134carried jointly by the floor 113 and by the shell 112 of the container111. Also the inner piston 115B has an upper position shown in brokenlines in FIG. 3, wherein it is disposed entirely within the upperportion of the outer piston 115A; and the outer piston 115A has an upperposition shown in broken lines in FIG. 3, wherein it is disposedadjacent to the roof 114 of the container 111 as established by thevolume control safety valve, not shown.

In the operation of the gasholder 110,, when the gas to be stored isfirst admitted into the container 111 below the piston sections 115A and115B and below the diaphragm sections 12A and B, the inner pistonsection 115B first rises within the outer piston section 115A and intoits upper position, as shown in broken lines in the middle of FIG. 3. Atthis time, further upward move- 1 ment of the inner piston section 115Brelative to the outer the container 111. When the lower portion of thecontainer 111 is completely full of the gas to be stored, the outerpiston section 1115A is moved into its upper'position carrying the innerpiston section 115B therewith and into the positions as shown in brokenlines at the top of FIG. 3. i

In the gasholder 110, the shell 112 has an inner radius of Rs and acorresponding inner circumferential length of Cs; the outer fender 116Ahas an outer radius of Rlfo and a corresponding outer circumferentiallength of Clyo; the outer fender 116A has an inner radius of Rlfi and acorresponding inner circumferential length of Clfi, the inner fender11613 has an outer radius of R2f0 and a corresponding outercircumferential length of CZfo; the outer diaphragm section 1253A has anunstrained radius Rld and a corresponding unstrained circumferentiallength Cld; and the inner diaphragm section 126B has an unstrainedradius RZd and a corresponding unstrained circumferential length C2d. Inthe gasholder 116, Cs is equal to about 101% to about 104% to Clfo, andClfi is equal to about 101% to about 104% of C2fo. Cld is equal to about/z(Cs-}-Cl 0) and C2d is equal to about The mode of constructing thegasholder lltl is substantially the same as that employed inconstructing the gasholder 1% as previously described Specifically, thebottom of the outer wall 121A of the outer diaphragm section 120A isstretched circumferentially from about 0.6% to about 2% of theunstrained circumferential length Cld and is sealed to the adjacentannular portion of the shell 112; and similarly, the bottom of the innerwall 122A of the outer diaphragm section 120A is compressedcircumferentially by about 0.6% to about 2% of the unstrainedcircumferential length Cld thereof, without inducing wrinkles across theloop of the material and is sealed to the adjacent annular portion ofthe outer piston section 115A. Specifically, the bottom of the outerwall 121B of the inner diaphragm section 120B is stretchedcircumferentially by about 0.6% to about 2% of the unstrainedcircumferential length C2d thereof and is sealed to the adjacent annularportion of the outer piston 115A; and similarly, the bottom of the innerWall 1228 of the inner diaphragm section 12913 is compressedcircumferentially by about 0.6% to about 2% of the unstrainedcircumferential length C2d thereof, without inducing wrinkles across theloop of the material and is sealed plasticity, after setting thereof.

2 to the adjacent annular portion of the inner piston section 115B.

' Referring now to FIG. 4, there is shown a cross section of a body ofdiaphragm material 420 that is particularly suitable for the fabricationof the diaphragm 2% in the gas holder of FIGS. 1 and 2, and for thefabrication of the diaphragm sectionslZtlA and 1203 in the gasholder 110of FIG. 3; which body of diaphragm material 420 is of composite sandwichconstruction including a gas-impervious inner layer 425 and a resilientouter layer 426 intimately bonded together by an intermediate layer ofadhesive 427. The inner layer 425 is formed of a sheet of elastomericorganic material that is chemically inert to the gas that is stored inthe container of the gasholder and that is characterized by substantialstretchability in the circumferential direction of thc ultimatelyfabricated diaphragm; the outer layer 426 is formed of a body ofelastomeric organic material of cellular structure that is resistant toatmospheric gases and to Water vapor and that is characterized by bothsubstantial stretchability and substantial compressibility in thecircumferential direction of the ultimately fabricated diaphragm; andthe intermediate layer 427 is formed of a film of any suitable adhesivematerial that is characterized by substantial elasticity and flexibilityafter setting thereof. More particularly, the inner layer 425essentially comprises a textile-reinforcing fabric 425a that issuitablyembedded in a'body 425b of synthetic rubber or synthetic organicresinhaving the general properties of rubber; while the outer layer 426essentially comprises a cushion or mattress of foamed synthetic rubberor synthetic organic resin having the general properties of foamedrubber; and the intermediate layer essentially comprises a syntheticrubber adhesive or asynthetic organic resin adhesive having' the generalproperties of a rubber adhesive.' Preferably, the textile fabric 425acomprises cords that extend between the inner and outer perimeters ofthe ultimately fabricated diaphragm and that lend'great tensile strengththereto that is in the general range 180# to 600# per inch ofcircumferential length of the ultimately fabricated diaphragm; whichcords may be formed of nylon, rayon, etc.,

in the usual manner of the cords incorporated in the textile fabricsnormally utilized in the production of heavyduty tires for trucks,road-working machines, etc.

In a constructional example of the diaphragm mate- 7 rial 420, the innerlayer 425 has a thickness in the gen- I ferential direction of theultimately fabricated diaphragm by at least 10% of the unstrainedcircumferential length thereof and is compressible in thecircumferential direction when put in the loop form of the ultimatelyfabricated diaphragm by at least 4% of the unstrained circumfe rentiallength thereof without inducing wrinkles therein. In the diaphragmmaterial 420, the inner layer 425 constitutes a primary membrane havinga low permeability to the gas stored in the container, the intermediatelayer 427 constitutes a flexible bonding agent that may also have a lowpermeability to the gas stored in the container and also to atmosphericgases and to Water vapor, and the outer layer 426 serves fundamentallyas a cushion or mattress, so that this foamed material may be of eitherthe open-cell type or the closed-cell type, depending upon theparticular constituents thereof. More particularly, the intermediateadhesive layer 427 retains substantial Since the outer layer 426 isresilient, it is capable of readily peeling off from the adjacent innersurface of the associated shell and upon the adjacent outer surface ofthe associated fender and back again in the normal operation of theultimately fabricated diaphragm, as previously explained.

. In the diaphragm material 420, the outer layer 426 contributessuflicient body and mass thereto that short forced nitrile rubber,polysulfide rubber, polychloroprene, Chemigum SL, Ensolite, orpolyurethane resin; the

outer layer 426 is formed of foamed nitrile rubber, polysulfide rubber,chloroprene, Chemigum SL, Ensolite or polyurethane resin; and theintermediate adhesive layer 427 is formed of Hycar rubber cement,Pliobond rubber cement, Chemigum SL resin cement or polyurethane resincement.

A particularly advantageous construction of phragm material 426comprises the inner' layer 425 formed of textile fabric reinforcednitrile rubber, the

outer layer 426 formed of foamed polyurethane and the intermediateadhesive layer 427 formed of Hycar rubber cement.

Referring now to FIG. 5, the modified form of the diaphragm material 520there illustrated is fundamentally of the same construction as that ofthe diaphragm ma? terial 420 as described in conjunction with FIG. 4;which diaphragm material 520 comprises the gas-impervious inner layer525 and the resilient outer layer'526 intimately bonded together by theintermediate layer of adhesive 527. In this case, the inner layer 525comprises a simple sheet of elastomeric organic material that ischemically inert to the gas that is stored in the container of thegasholder and that is characterized by substantial stretchability in thecircumferential direction of the ultimately fabricated diaphragm,whereby the inner layer 525 constitutes a primary membrane having a lowpermeability to the gas stored in the container. Specifically, the innerlayer 525 may be formed of a sheet of nitrile Iubber, polysulfiderubber, polychloroprene, Chemigum SL, Ensolite, Mylar or polyurethaneresin, whereas the outer layer 526 and the intermediate layer 527 may beformed of the materials as previously explained in conjunction With thecorresponding layers 426 and 427.

In a constructional example of the diaphragm mate rial 520, the innerlayer 525 has a thickness in the general range 0.010" to 0.060" and ispreferably formed of Mylar, the outer layer 526 has a thickness in thegeneral range A" to /2" and is preferably formed of foamed polyurethaneresin, and the intermediate layer 527 has 7 a thickness in the generalrange one to several mils and;

is preferably formed of Hycar rubber cement; whereby the compositediaphragm material 520 is elastomeric and is stretchable in thecircumferential direction of the 'loop form of the ultimately fabricateddiaphragm by at least 4% of the unstrained circumferential lengththere'- ofwithout inducing wrinkles therein.

Referring now to FIG. 6, the modified'form of the diaphragm material 620there illustratedcomprises a combination of the constructions of thediaphragm materials 420 and 520 as described in conjunction with FIGS. 4and 5; which diaphragm material 620 comprises the gasirnpervious innerlayer 625, the resilient outer layer 626, the gas-imperviousintermediate layer 627, the intermediate layer of adhesive 627a bondingtogether the layers 625 and 627, and the intermediate layer of adhesive6271) bonding together the layers 626 and 627. In this case, the innerlayer 625 comprises a simplesheet of elastorneric organic materialcorresponding to the inner layer 525, the

These characthe dia-.

- 620, the inner layer 625 has a thickness in the general range 0005" to0.030" and is preferably formed of Mylar, the intermediate layer 627 hasa thickness in the general range 0.005" to 0.030" and is preferablyformed of textile fabric reinforced nitrile rubber, the outer layer 626has a thickness in the general range A" to /2" and is preferably formedof foamed polyurethane resin,and each of the intermediate layers 627aand 627]) has a thickness in the general range one to several mils andis preferably formed of Hycar rubber cement; whereby the compositediaphragm material 620 is elastomeric and is stretchable in thecircumferential direction of the ultimately fabricated diaphragm by atleast of the unstrained circumferential length thereof and iscompressible in the circumferential direction when put in the loop formof the ultimately fabricated diaphragm by at least 4% of the unstrainedcircumferential length thereof without inducing wrinkles therein.

Consider now the chemical definitions of the foregoing namedcompositions.

Nitrile rubber (GR-A) essentially comprises copolymers of butadiene andacrylonitrile and has the generalized formula:

[('CH2 CH=CH OH2 r-CHCH1] N Polysulfide rubber has the generalizedformula:

['"CII2CH2fi|SI ]n s s Polychloroprene (GR-M) has the generalizedformula:

or+n o=orr-o11 n ChemigumSL comprises a polyester of ethylene glycol andpropylene glycol and adipic acid (to produce a linear polymer) that hasbeen reacted with a diisocyanate (to produce urethane cross linkages).

Ensolite comprises a nitrile rubber (copolymers of butadiene andacrylonitrile) modified by a content 0 about 25% by weight of polyvinylchloride resin.

4 Mylar comprises a polyester of ethylene glycol and terephthalic acid.

A typical polyurethane comprises polymers produced by the additionreaction between a polyisocyanate and a hydroxl-rich compound (at least2 hydroxl groups per molecule); such as glycols', polyesters,polyethers, etc.

Hycar rubber cement comprises a nitrile rubber (copolymers of butadieneand acrylonitrile) modified by a content of a few percent by weight ofphenolic resin, as

well as a plasticizer (normally dioctylphthalate).

Pliobond rubber cement comprises a nitrile rubber (copolymers ofbutadiene and acrylonitrile) modified by a few percent by weight of areinforcing resin (such as polyvinyl chloride) and a suitableplasticizer.

Chemigum SL resin cement comprises Chemigurn SL resin modified by a fewpercent by weight of a rein: forcing resin and a suitable plasticizer.

Polyurethane resin cement comprises polyurethane resin modified by a fewpercent by weight of a reinforcing resin and a suitable plasticizer.

The foregoing compositions are vastly superior to natural rubber withrespect to resistance to swelling and to deterioration in the presenceof petroleum products, with respect to chemical inertness in thepresence of a wide variety of gases that may be stored in the containerof the gasholder, with respect to resistance to atmospheric gases, watervapor, ozone and aging, and with respect to a low permeability to a widevariety of gases that may be stored in the container of the gasholderand to atmospheric gases and to water vapor; whereby the diaphragmmaterials 420, 520 and 620 have an exceedingly long useful life in theultimately fabricated diaphragms of the gasholders.

In the diaphragm constructions 420, 520 and 620, as respectively shownin FIGS. 4 to 6, inclusive, the inner and outer layers of material areseparate and distinct with respect to each other, either beingchemically identical or totally dissimilar, and bonded together by aseparate and distinct intermediate layer. However, it should be readilyunderstood that a suitable diaphragm of the character described may alsobe constructed by foaming-the rubber or other plastic material directlyonto the inner gas-impervious film or fabric layer, thus obviating anydistinct intermediate layer of bonding material. Also, it is possible toform a surface on a body of foamed rubber or plastic material that isinert and impervious to gas to be stored, by sealingsuch surface,employing either a heat treatment or a chemical treatment. f g

In view of the foregoing, it is apparent that there has been provided ina dry-seal puressure-type gasholder, an

improved diaphragmof composite construction that is capable of feedingin either direction between the inner surface of the shell of thecontainer and the outer surface of the fender carried by the piston,without inducing wrinkles, folds or creases therein, whereby thediaphragm has an exceedingly long useful life in the gasholder.Furthermore, the composite diaphragm is fabricated of a plurality oflayers of componentmaterialsthat are especially selected to impart tothe diaphragm the required elastomeric properties, to resist chemicalattack by a wide variety of gases stored in the gasholder, to resistoxidation and aging in the presence of such stored gases, atmosphericgases and water vapor andto provide a composite diaphragm that has anexceedingly low permeability to the stored gases and to atmosphericgases and to water vapor. r

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to. coverin the appended claims all such modifications as fall within the truespirit and scope of the invention.

What is claimed is:

.1. In a dry-seal pressure-type: gasholder, a containerincluding anupstanding substantially cylindrical shell, a

substantially disk-shaped piston arranged in said container and movablein the vertical direction, an upstanding substantially cylindricalfender carried by said piston adjacent to the circumference thereof andspaced radially inwardly with respect to said shell to provide anannular space therebetween, and :an annular curtain-like gas-imperviousflexible diaphragm arranged in an upwardly directed annular loop in saidannular space, said diaphragm including an annular outer wall sealedadjacent to the bottom thereof to an annular portion of said shell andan annular inner wall sealed adjacent to the bottom thereof to anannular portion of said piston and an annular connecting wall extendingbetween the top of said outer wall and the top of said inner wall, saiddiaphragm being formed of elastomeric material and having a thickness ofat least about A", the circumferential length of said diferential lengthCd, said fender having an outer circumferential length Cf, wherein Cs CdCf, the material in said outer wall being constantly stretched and thematerial in said inner wall being constantly compressed when saiddiaphragm is put in place, the gas under pressure in said containerproducing constant circumferential strains in the material in saiddiaphragm so as to stretch the material in said outer wall into firmengagement with the inner surface of said shell and to compress thematerial in said inner wall into firm engagement with the outer surfaceof said fender, whereby vertical movement of said piston effects thefeed of the material in said diaphragm between said outer wall and saidinner wall through said connecting wall and the consequent reversal ofthe cir cumferential strains in the material thus fed, all withoutinducing wrinkles in said diaphragm.

2. The gasholder set forth in claim 1, wherein Cs is equal to about 101%to about 104% of C and Cd is equal to about /z(Cs+Cf).

3; In a dry-seal pressure-type gasholder, a container including anupstanding substantially cylindrical shell, a first substantiallyannular piston arranged in said container and movable in the verticaldirection, a first upstanding substantially cylindrical fender carriedby said first piston and spaced radially inwardly with respect to saidshell to provide a first annular space therebetween, a first annularcurtain-like gas-impervious flexible diaphragm arranged in an upwardlydirected annular loop in said first annular space, said first diaphragmincluding a first annular outer wall sealed adjacent to the bottomthereof to anannular portion of said shell and a first annular innerwall sealed adjacent to the bottom thereof to an annular portion of saidfirst piston and a first annular connecting wall extending between thetop of said first outer wall and top of said first inner wall, a secondsubstantially diskshaped piston arranged in said container and movablein the vertical direction, asecond upstanding substantially cylindricalfender carried by said second piston and spaced radially inwardly withrespect to said first fender to provide a second annular spacetherebetween, and a second annular curtain-like gas-impervious flexiblediaphragm arranged in an upwardly directed annular loop insaid secondannular space, said second diaphragm including a second annular outerwall sealed adjacent to the bottom thereof to an annular portion of saidfirst piston and a second annular inner wall sealed adjacent to thebottom thereof to an annular portion of said second piston and a secondannular connecting wall extending between the top of said second outerwall and the top of said second 'inner wall, each ofsaid diaphragmsbeing formed of the material in said first outer wall being constantlystretched and the material in said first inner wall being constantlycompressed when said first diaphragm is put in place, the gas underpressure in said container producing constant circumferential strains inthe material in said first diaphragm so as to stretch the material insaid first outer wall into firm engagement with the inner surface ofsaid shell and to compress the material in said first inner wall intofirm engagement with the outer surface of said first fender, wherebyvertical movement of said first piston effects the feed of the materialin said first diaphragm between said first outer wall and said firstinner wall through said first connecting wall and the consequentreversal of the circumferential strains in.the material thus fed, allwithout inducing wrinkles in said first diaphragm, the-material insaid'secondrouter Wall being constantly stretchedand thematerial in saidsecond inner wall being outer wall and said second inner wall throughsaid second connecting wall and the consequent reversal of thecircumferential strains in the material thus fed, all without inducingWrinkles in said second diaphragm.

4. The gasholder set forth in claim 3, wherein Cs is equal to about 101%to about 104% of Clfo, Cdlis equal to about /2(Cs+Clf0), Clfi is equalto about 101% to about 104% of C2f0, and Cd2 is equal to about/2(Clfi-{C2f0).

5. In a dry-sealpressure-type gasholder, a container ineluding anupstanding substantially cylindrical shell, a

substantially cylindrical piston arranged in said container and movablein the vertical direction, said piston being spaced radially inwardlywith respect to said shell to provide an annular space therebetween, andan annular curtain-like gas-impervious flexible diaphragm arranged in anupwardly directed annular loop in saidannular space, said diaphragmincluding an annular outer wall sealed adjacent to the bottom thereof toan annular portion of said shell and an annular inner wall sealedadjacent to the bottom thereof to an annular portion of said piston andan annular connecting wall extending between the top of said outer walland the top of said inner wall, whereby vertical movement of said pistonin saidshell effects the feed of the material in said diaphragm betweensaid outer and inner walls .via said connecting wall and the consequentreversal of the circumferential strains in the material thus fed, saiddiaphragm being formed of elastomeric material and having a thickness ofat least about A", the circumferential length of said diaphragm beingboth stretchable and compressible by about 0.6% to about 2% of theunstrainedcircumferential length thereof without inducingwrinkles in thematerial therein.

6. In a dry-seal. pressure-type gasholder including a substantiallycylindrical container and a substantially cylindrical piston axiallymovably arranged in said container, said piston being spaced radiallyinwardly with re,- spect to said container to provide an annular spacetherebetween, a substantially ring-like flexible diaphragm arranged insaid annular space and sealed adjacent to the outer perimeter thereof tosaid container and sealed adjacent to the inner perimeter thereofto saidpiston, wherein said diaphragm has an inner side in contactwith the gasin said container and an outer side-in contact with the at-' mosphere,whereby axial movement of said piston in said container effects the feedof the material in said diaphragm between the outer portionthereofdisposed adjacent to, said container and the inner portionthereof disposed adja-,

cent to said piston and the consequent reversal of the circumferentialstrains in the material thus fed; said diaphragm being of compositeconstruction including a gasimpervious inner layer'and a resilient outerlayer intimately bonded together, said inner layer being relatively thinand formed of elastomeric organic material that is chemically inert tothe gas stored in said container and that is characterized bysubstantial stretchability in the circumferential direction of saiddiaphragm, said outer layer being relatively thick and formed ofelastomeric organic material that is resistant to atmospheric gases andto about 2% of the unstrained circumferential length thereof withoutinducing Wrinkles in the material therein.

7. The gasholder set forth in claim 6, wherein said composite diaphragmhas a tensile strength between the inner and outer perimeters thereof inthe range 180 pounds to 600 pounds per inch of circumferential lengththereof.

8. The gasholder set forth in claim 6, wherein said inner layer has athickness in the range 0.010" to 0.060 and said outer layer has athickness in the range A" to /2".

9. The gasholder set forth in claim 6, wherein said outer layeressentially comprises a closed-cell synthetic organic resin.

10. The gasholder set forth in claim 6, wherein said outer layeressentially comprises an open-cell synthetic organic resin.

11. In a dry-seal pressure-type gasholder including a substantiallycylindrical container and a substantially cylindrical piston axiallymovably arranged in said container, said piston being spaced radiallyinwardly with respect to said container to provide an annular spacetherebetween, a substantially ring-like flexible diaphragm arranged insaid annular space and sealed adjacent to the outer perimeter thereof tosaid container and sealed adjacent to the inner perimeter thereof tosaid piston, wherein said diaphragm has an inner side in contact withthe gas in said container and an outer side in contact with the atmosphere, whereby axial movement of said piston in said containereflects the feed of the material in said diaphragm between the outerportion thereof disposed adjacent to said container and the innerportion thereof disposed adjacent to said piston and the consequentreversal of the circumferential strains in the material thus fed; saiddiaphragm being of composite sandwich construction including agas-impervious inner layer, a resilient outer layer, and an intermediatelayer of adhesive firmly securing together said inner and outer layers,said inner layer being relatively thin and formed of elastomeric organicmaterial that is chemically inert to the gas stored in said containerand that is characterized by substantial stretchability in thecircumferential direction of said diaphragm, said outer layer beingrelatively thick and formed of elastomeric organic material that isresistant to atmospheric gases and to Water vapor and that ischaracterized by both substantial stretchability and substantialcompressibility in the circumferential direction of said diaphragm, saidintermediate layer being relatively thin and formed of organic materialthat is characterized by substantial elasticity and flexibility aftersetting thereof, said composite diaphragm having a thickness of at leastabout A", the circumferential length of said composite diaphragm beingboth stretchable and compressible by about 0.6% to about 2% of theunstrained circumferential length thereof without inducing wrinkles inthe material therein.

12. In a dry-seal pressure-type gasholder including a substantiallycylindrical container and a substantially cylindrical piston axiallymovably'arranged in said container, said piston being spaced radiallyinwardly with respect to said container to provide an annular spacetherebetween, a substantially ring-like flexible diaphragm arranged insaid annular space and sealed adjacent to the outer perimeter thereof tosaid container and sealed adjacent to the inner perimeter thereof tosaid piston, wherein said diaphragm has an inner side in contact withthe gas in said container and an outer side in contact with theatmosphere, whereby axial movement of said piston in said containereffects the feed of the material in said diaphragm between the outerportion thereof disposed adjacent to said container and the innerportion thereof disposed adjacent to said piston and the consequentreversal of the circumferential strains of the material thus fed; saiddiaphragm being of composite construction including a gas-imperviousinner layer and a resilient outer layer intimately bonded together, saidinner layer being formed of a relatively thin sheet of elastomericsynthetic organic resin that is chemically inert'to the gas stored insaid container and that is characterized by substantial stretchabilityin the circumferential direction of said diaphragm, said outer layerbeing formed of a relatively thick mattress of foamed elastomericsynthetic organic material that is resistant to atmospheric gases and towater vapor and that is characterized by both substantial stretchabilityand substantial compressibility in the circumferential direction of saiddiaphragm, said composite diaphragm having a thickness of at least aboutA", the circumferential length of said composite diaphragm being bothstretchable and compressible by about 0.6% to about 2% of the unstrainedcircumferential length thereof without inducing wrinkles in the materialtherein. p

13. In a dry-seal pressure-type gasholder including a substantiallycylindrical container and a substantially cylindrical piston axiallymovably arranged in said container, said piston being spaced radiallyinwardly with respect to said container to provide an annular spacetherebetween, a substantially ring-like flexible diaphragm arranged insaid annular space and sealed adjacent to the outer perimeter thereof tosaid container and sealed adjacent to the inner perimeter thereof tosaid piston, wherein said diaphragm has an inner side in contact withthe gas in said container and an outer side in contact with theatmosphere, whereby axial movement of said piston in said containerefliects the feed of the material in said diaphragm between the outerportion thereof disposed adjacent to said container and the innerportion thereof disposed adjacent to said piston and the consequentreversal of the circumferential strains in the material thus fed; saiddiaphragm being of composite sandwich construction including agas-impervious inner layer of organic material, 7

a resilient outer layer of organic material, an intermediate layer oftextile fabric, a first layer of adhesive bonding said inner layer tosaid intermediate layer, and a second layer of adhesive bonding saidouter layer to said intermediate layer, said inner layer beingrelatively thin and elastomeric and characterized by substantialstretchability in the circumferential direction of said diapragm, saidouter layer being relatively thick and elastomeric and characterized byboth substantial stretchability and substantial compressibility in thecircumferential direction of said diapragm, said intermediate layerbeing relatively thin and elastic and characterized by great tensilestrength in the radial direction between the inner and outer perimetersof said diaphragm and by both substantial stretchability and substantialcompressibility in the circumferential direction of said diaphragm, eachof said adhesive layers being relatively thin and characterized bysubstantial elasticity and flexibility after setting thereof, saidcomposite diaphragm having a thickness of at least about A, thecircumferential length of said composite diaphragm being bothstretchable and compressible by about 0.6% to about 2% of the unstrainedcircumferential length thereof without inducing Wrinkles in the materialtherein.

14. In a dry-seal pressure-type gasholder including a substantiallycylindrical container and a substantially cylindrical piston axiallymovably arranged in said container, said piston being spaced radiallyinwardly with respect to said container to provide an annular spacetherebetween, a substantially ring-like flexible diaphragm arranged insaid annular space and sealed adjacent to the outer perimeter thereof tosaid container and sealed adjacent to the inner perimeter thereof tosaid piston, wherein said diaphragm has an inner side in contact withthe gas in said container and an outer side in contact with theatmosphere, whereby axial movement of said piston in said containerelfects the feed of the material in said diaphragm between the outerportion thereof disposed adjacent to said container and the innerportion thereof disposed adjacent to said piston and the consequentreversal of the circumferential strains in the material thus fed; saiddiaphragm being formed essentially of foamed elastomeric material thatis characterized by resiliency and by both 15 circumferentialstretchability and circumferential compressibility, said material alsobeing resistant to atmospheric gases and to Water vapor, said materialof the inner side of said diaphragm also being both inert and highlyimpervious to the gas stored in said container, said diaphragm having athickness in the general range A" to /2", the circumferential length ofsaid diaphragm being both stretchable and compressible by about 0.6% toabout 2% of the unstrained circumferential length thereof withoutinducing wrinkles in the material therein.

References Cited in the file of this patent UNITED STATES PATENTS IWiggins Aug. 9, 1949 Byrd et a1. Jan. 31, 1950 Breit Nov. 28, 1950'Allen Aug. '12, 1952 7 Allen Mar' 10, 1953 Wiggins et a1. Nov. 15, 1955Wiggins July 24, 1956 Woodard et a1. Apr. 3, 1962

5. IN A DRY-SEAL PRESSURE-TYPE GASHOLDER, A CONTAINER INCLUDING ANUPSTANDING SUBSTANTIALLY CYLINDRICAL SHELL, A SUBSTANTIALLY CYLINDRICALPISTON ARRANGED IN SAID CONTAINER AND MOVABLE IN THE VERTICAL DIRECTION,SAID PISTON BEING SPACED RADIALLY INWARDLY WITH RESPECT TO SAID SHELL TOPROVIDE AN ANNULAR SPACE THEREBETWEEN, AND AN ANNULAR CURTAIN-LIKEGAS-IMPERVIOUS FLEXIBLE DIAPHRAGM ARRANGED IN AN UPWARDLY DIRECTEDANNULAR LOOP IN SAID ANNULAR SPACE, SAID DIAPHRAGM INCLUDING AN ANNULAROUTER WALL SEALED ADJACENT TO THE BOTTOM THEREOF OF AN ANNULAR PORTIONOF SAID SHELL AND AN ANNULAR INNER WALL SEALED ADJACENT TO THE BOTTOMTHEREOF TO AN ANNULAR PORTION OF SAID PISTON AND AN ANNULAR CONNECTINGWALL EXTENDING BETWEEN THE TOP OF SAID OUTER WALL AND THE TOP OF SAIDINNER WALL, WHEREBY VERTICAL MOVEMENT OF SAID PISTON IN SAID SHELLEFFECTS THE FEED OF THE MATERIAL IN SAID DIAPHRAGM BETWEEN SAID OUTERAND INNER WALLS VIA SAID CONNECTING WALL AND THE CONSEQUENT REVERSAL OFTHE CIRCUMFERENTIAL STRAINS IN THE MATERIAL THUS FED, SAID DIAPHRAGMBEING FORMED OF ELASTOMERIC MATERIAL AND HAVING A THICKNESS OF AT LEASTABOUT 1/4", THE CIRCUMFERENTIAL LENGTH OF SAID DIAPHRAGM BEING BOTHSTRETCHABLE AND COMPRESSIBLE BY ABOUT 0.6% TO ABOUT 2% OF THE UNSTRAINEDCIRCUMFERENTIAL LENGTH THEREOF WITHOUT INDUCING WRINKLES IN THE MATERIALTHEREIN.